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How Regular Maintenance Keeps Your Furnace Working Efficiently

March 2, 2015

Why Maintain Your Furnace?

The furnace is a big ticket item in most homes across the nation. Furnaces are responsible for heating air and distributing it throughout the home, creating a consistent environment that is so crucial for comfortable living, especially during winter months. This means that furnace maintenance and efficiency can make a big impact on the comfort of the home and the utility bill.

How to Measure Efficiency

Furnace efficiency is measured by examining annual fuel utilization efficiency (AFUE). The AFUE rating is a measurement of how efficient the furnace is at converting energy to heat over the course of a year. This number is measured as a percentage of the fuel used by the system versus the heat produced. For example, an AFUE rating of 90% demonstrates that 90% of the fuel used by the system was converted to heat, and that 10% of that energy was lost, or inefficient in its conversion. This heat loss does not factor in the location of the heat ducts in the home or any other environmental factors.

The AFUE measurement is required to be displayed on modern furnaces so that the buyer can take the AFUE of each model into consideration during the purchasing process. The minimum AFUE rating for a furnace is 75-78% depending on the type of furnace and its intended home use. The overall efficiencies of a furnace can also be determined by factoring in additional features, including whether or not the system has a continuous pilot light, is sized correctly for the home, and whether the system is sealed or relies on natural draft combustion.

How to Maintain Efficiency

The key to an efficiently running system within the home is properly conducting routine maintenance. A properly maintained system will save money and extend the life of its parts. Along with many other home systems, yearly maintenance of a furnace is a must. Proper care and prevention can come at a much cheaper price than repair.


All systems should be checked routinely for signs of needed repair, including the following areas:

  • The condition of vent connection pipes and chimneys should be checked.
  • Heat exchangers should be checked for leaks.
  • Controls should be adjusted to ensure proper water and air temperature settings are configured for ideal efficiency.


Many older systems can also be retrofitted to help increase the efficiency and grant the system additional life. It’s important to weigh the cost of replacing a furnace against the cost to retrofit, especially if the system is already near the end of its life. Retrofitting can improve a system through the installation of programmable thermostats, upgraded ductwork, or zone control.


If retrofitting is not the ideal solution, replacing the system entirely with an updated model can greatly increase the efficiency of the furnace, helping it begin to pay for itself immediately. It can also decrease a home’s environmental impact by reducing its carbon emissions.

If the existing furnace is aged, oversized (as many older furnaces are), or in disrepair, replacing it with a high efficiency model is a great next step. This can be paired with an overall home energy efficiency overhaul, oftentimes allowing a homeowner to purchase a smaller unit and receive the same level of performance and output.

Regular maintenance of a furnace is critical for keeping it running efficiently, prolonging its life, lowering a home’s environmental impact, and maintaining a pleasant home environment. Efficiency of a replacement system can be preserved by taking note of the furnace’s AFUE rating, and also ensuring that the remainder of the home has been evaluated for efficiency prior to new system implementation.

About The Author

Bob Jenson

For over 45 years, Bob Jenson has been providing quality heating and air services to the San Diego community.

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